JPH0135926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for spinning polyester fibers, and more particularly to a method for melt-spinning polyester at a take-up speed of 2000 m/min or more.

Polyesters, typified by polyethylene terephthalate, have many excellent properties and are therefore widely used in various applications, particularly in fibers. Polyester fibers are usually melt-spun, drawn,
It is ready for use after heat setting. In recent years, advances in silk spinning technology have made it possible to significantly increase the take-up speed during melt spinning from the conventional 1000 to 1500 m/min to 2000 m/min or more, and even to 2500 to 4000 m/min. In particular, increase the withdrawal speed to 2500~
The intermediately oriented undrawn yarn obtained at a speed of 4000 m/min is usually directly subjected to stretching, false twisting and crimping, and in recent years, this use has been making remarkable progress and is becoming the mainstream of yarn spinning technology.

On the other hand, attempts have been made to further increase the take-up speed to 4000 m/min or higher. However, such ultra-high-speed spinning has the drawback that yarn breakage occurs frequently during spinning, and furthermore, the strength of the product yarn decreases. In order to eliminate this drawback, attempts have been made to optimize the spinning conditions, such as spinning temperature, cooling air volume, and cooling air temperature, and to improve the structure of the spinning tube and spinneret nozzle, but these measures have limitations. We cannot expect major improvements.

The inventor studied the causes of the above drawbacks, and
Polyester has the property of being difficult to crystallize compared to polyethylene, polyamide, etc., but when the take-up speed during melt spinning exceeds 2000 m/min, molecular orientation occurs and crystallization occurs along with this. It has been found that this tendency becomes particularly noticeable at speeds of 4,000 m/min or more, and that crystallization progresses significantly even though the orientation of the spun yarn has not progressed sufficiently, which causes the above-mentioned drawbacks. Based on this fact, we further investigated the crystallization behavior of polyester, which is highly oriented and has low crystallinity during high-speed spinning, and found that the antimony compound used as a polymerization catalyst for polyester acts as a nucleating agent for polyester. More surprisingly, it was found that this antimony compound has an effect, although not sufficient, in suppressing crystallization during molecular orientation during high-speed spinning.

Furthermore, as a result of investigating various additives to suppress crystallization during molecular orientation, it was discovered that a remarkable effect was observed by adding and copolymerizing a polymer of adipic acid and 1,3-butylene glycol. . The present invention was completed as a result of further studies based on these findings.

That is, in the present invention, when polyester is melt-spun at a drawing speed of 2000 m/min or more, the polyester has ethylene terephthalate as its main constituent unit, and the acid constituting the polyester is added at any stage before the polycondensation reaction is completed. for the ingredients
0.01 to 2.0% by weight of the following formula (1) OH [-OC-(CH ₂ ) _x -COO-(CH ₂ ) _y -O-] _o H
...(1) A polyester fiber spinning method characterized by using a polyester obtained by addition copolymerizing an aliphatic polyester represented by X = 0 to 10 Y = 2 to 10 n = 2 to 100 .

The polyester referred to in the present invention mainly refers to polyethylene terephthalate consisting of a terephthalic acid component and an ethylene glycol component, but a portion (usually 20 mol% or less) of the terephthalic acid component is replaced with another difunctional carboxylic acid component. It may be a substituted polyester, or a polyester in which a part (usually 20 mol% or less) of the ethylene glycol component is replaced with another diol component. Furthermore, the polyester may be copolymerized or mixed with various additives, such as dye-facilitating agents, flame retardants, antistatic agents, hydrophilic agents, colorants, etc., as necessary.

Such polyesters are usually produced by esterifying terephthalic acid and ethylene glycol, by transesterifying a lower alkyl ester of terephthalic acid such as dimethyl terephthalate with ethylene glycol, or by reacting terephthalic acid with ethylene oxide. It is produced by producing a glycol ester of terephthalic acid and/or a low polymer thereof, and then heating this product under reduced pressure to cause a polycondensation reaction until a predetermined degree of polymerization is achieved.

In _{the present} invention, _the aliphatic polyester HO [-OC-( _CH2 ) _oH
...(1) A polyester obtained by addition copolymerization of X=0 to 10, Y=2 to 10, and n=2 to 100 is melt-spun. The above-mentioned aliphatic polyester can be easily obtained by an esterification reaction and a polycondensation reaction of an aliphatic dicarboxylic acid and a diol. Representative aliphatic dicarboxylic acids include oxalic acid where X = 0, malonic acid where X = 1, succinic acid where X = 2, glutaric acid where X = 3, adipic acid where X = 4, and pimelic acid where X = 5. ,
X=6 suberic acid, X=7 azelaic acid,
Typical diols include sebacic acid with Y=8, ethylene glycol with Y=2, and sebacic acid with Y=3.
Examples include propylene glycol with Y=4 and butylene glycol with Y=4. If the amount of such aliphatic polyester used is too small, the effect of suppressing oriented crystallization will not be obtained, and on the other hand, if the amount is too large, the softening point of the resulting polyester will decrease or the yellowish color will increase, so it is not used as a raw material for polyester. The amount may be appropriately selected in the range of 0.01 to 2.0% by weight, preferably 0.05 to 1.0% by weight based on the bifunctional carboxylic acid. Further, it may be added at any time until the polyester production reaction is completed, and it may be added at the same time as other additives used in polyester production, such as catalysts and stabilizers. In addition, when adding, it may be added as it is, or it may be added after being dispersed or dissolved in a suitable solvent such as glycol.

When melt spinning is performed using the polyester produced by the method of the present invention at a take-up speed of 2,000 m/min or more, oriented crystallization is suppressed especially in the high speed spinning region of 4,000 m/min or more. In addition to a significant reduction in yarn breakage, the strength of the yarn also tends to increase. Note that as the spinning conditions, polyester melt spinning conditions can be arbitrarily adopted.

Next, the present invention will be explained in further detail by giving examples. In the examples, parts are parts by weight, and [η] is the extreme viscosity determined from the value measured at 30°C in an orthochlorophenol solvent. The L value and b value, which represent the color tone of the polymer, are values measured using a Hunter type color difference meter, and the larger the L value, the more the whiteness is improved, and the larger the b value, the stronger the yellowish tinge. It shows. Also, 100 yarns (2.5Kg winding) were broken during spinning.
It is indicated by the number of yarn breaks during winding.

Example 970 parts of dimethyl terephthalate, 640 parts of ethylene glycol, and 0.31 part of manganese acetate as a transesterification catalyst (25 mmol% to dimethyl terephthalate) were stirred and then charged into a reactor equipped with a rectification column and a methanol distillation condenser. 140℃ to 230℃
The transesterification reaction was carried out while the methanol produced as a result of the reaction was distilled out of the system. Three hours after the start of the reaction, the internal temperature reached 230°C, and 320 parts of methanol was distilled out. Here, 0.18 parts of trimethyl phosphate (25 mmol% vs. dimethyl terephthalate) was added as a stabilizer, and after reacting for 10 minutes, 0.44 parts of antimony trioxide (30 mmol% vs. dimethyl terephthalate) was added as a polycondensation catalyst. 2.91 parts of titanium dioxide was added as an agent, and adipic acid-butylene glycol polyester (degree of polymerization =
10) 9.7 parts (1.0% by weight vs. dimethyl laphthalate)
was added and allowed to react for 20 minutes to complete the transesterification reaction. Next, the obtained reaction product was transferred to a polycondensation reactor equipped with a stirrer and a glycol condenser, and the polycondensation reaction was carried out while gradually raising the temperature from 230°C to 285°C and lowering the pressure from normal pressure to a high vacuum of 1 mmHg. I let it happen. Polycondensation reaction time 3 hours 30 minutes [η] 0.64, softening point 260.8℃, hue L value 71.5, b value
A polymer of 7.8 was obtained.

This polymer was spun at a spinning temperature of 290℃ and a discharge amount of 38g/
minute, cooling wind linear velocity 15 m/min (26°C, relative temperature 70
%), and a 115 denier/36 filament intermediately oriented yarn was wound at a take-up speed of 3000 m/min. This intermediately oriented yarn has a Δn (birefringence index) of 0.055, a hot water shrinkage rate (shrinkage rate after 30 minutes of treatment in hot water at 60°C) of 61%, and a strength of 2.8.
g/denier and elongation of 132%, and there were no yarn breakages during spinning.

Next, this intermediately oriented yarn was stretched with a high-speed false twisting machine using a urethane disc at a stretching ratio of 1.53 times and a heater temperature.
A processed yarn of 75 denier/36 filaments was wound at 220°C and at a yarn speed of 700 m/min. No processing yarn breakage was observed.

Separately, the above polymer was spun at a spinning temperature of 290℃ and a discharge amount of
75 denier/24 at 40g/min, cooling air velocity 15m/min (26℃, relative humidity 70%), take-up speed 5000m/min
I wound up the filament. This filament△
The strength was sufficient: n0.103, elongation 57%, and strength 3.9 g/denier, and there were no yarn breakages during spinning.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the adipic acid-butylene glycol polyester was not added. The obtained polymer had a softening point of [η] 0.64.
The temperature was 262.5°C, the hue L value was 71.0, and the b value was 8.0.

Intermediately oriented yarn obtained at a take-up speed of 3000 m/min is △
n0.045, hot water shrinkage rate 45%, strength 2.3g/denier,
The elongation was 120%, and five yarns were broken during spinning. When this intermediately oriented yarn was false-twisted, the number of broken yarns was 15, which was poor.

Further, the filament obtained at a take-up speed of 5000 m/min had a low strength of Δn 0.085, an elongation of 70%, and a strength of 3.2 g/denier, and was extremely poor with 20 yarns breaking during spinning.

Example 2 The same procedure as in Example 1 was conducted except that sebacic acid-propylene glycol polyester (degree of polymerization = 50) was used in place of the adipic acid-butylene glycol polyester used in Example 1. The obtained polymer had a softening point of [η] 0.64.
The temperature was 260.2°C, the hue L value was 71.6, and the b value was 7.5.

Intermediately oriented yarn obtained at a take-up speed of 3000 m/min is △
n0.054, hot water shrinkage rate 62%, strength 2.7g/denier,
The elongation was 134%, and there were no yarn breakages during spinning. When this intermediately oriented yarn was false-twisted, the number of broken yarns was zero, which was good.

Further, the filament obtained at a take-up speed of 5000 m/min had a Δn of 0.105, an elongation of 59%, a strength of 3.9 g/denier, and no yarn breakage occurred during spinning.

Example 3 860 parts of terephthalic acid and 390 parts of ethylene glycol
A portion of the mixture was placed in a pressure-resistant autoclave, and an esterification reaction was carried out at 220 to 260° C. for 3 hours under a pressure of 3 kg/cm ² G with N ₂ while distilling off the generated water. Approximately 180
0.04 parts of trimethyl phosphate (5 mmol% to terephthalic acid) as a stabilizer after 1 part of water was distilled off.
was added, and after 10 minutes, 0.45 parts of antimony trioxide (30 mmol% to terephthalic acid) and 8.60 parts of adipic acid-butylene glycol polyester (degree of polymerization 10) (1.0 wt% to terephthalic acid) were added as polycondensation catalysts. Furthermore, 2.58 parts of titanium dioxide was added as a matting agent, and the reaction was continued for 10 minutes to complete the esterification reaction. Next, a polycondensation reaction was carried out in the same manner as in Example 1, and [η] was 0.64 in a total polycondensation reaction time of 3 hours.
Polyethylene terephthalate was obtained with a softening point of 259.6°C, a hue L value of 68.1, and a b value of 5.0. Next, Example 1
The intermediately oriented yarn obtained by melt spinning in the same manner as above had △n0.057, hot water shrinkage rate of 62%, and strength of 2.8%/
The denier and elongation were 134%, there were no yarn breakages during spinning, and no yarn breakage was observed.

Furthermore, the filament obtained at a take-up speed of 5000 m/min had sufficient strength, Δn 0.117, elongation 58%, and strength 4.1 g/denier, and was extremely good with no yarn breakage during spinning.

Claims (1)

[Claims] 1. When polyester is melt-spun at a take-up speed of 2000 m/min or more, the polyester has ethylene terephthalate as its main constituent unit and is formed at any stage before the polycondensation reaction is completed. 0.01 to 2.0% by weight of the following formula (1) HO [-OC-( _CH2 ) _X -COO-( _CH2 ) _Y -O-] _o H based on the acid component
...(1) A method for spinning polyester fibers, characterized in that a polyester obtained by addition copolymerizing an aliphatic polyester represented by X=0-10, Y=2-10, and n=2-100 is used.